It is typical in data processing apparatus for implementing a system in printed circuit board (PCB) format, wherein space and other constraints call for accessory PCBs (daughter boards) to be disposed in orthogonal relation to principal PCBs (backplane boards). Connectors are required for electrically interconnecting the respective electrically conductive traces on the daughter boards and backplane boards, and include matable connector housings having contact sets permanently engaged with electrically conductive traces on the respective PCBs. The contact sets are mated with one another on mating of the connector housings. One such known connector is described in U.S. Pat. No. 4,655,518.
The '518 patent is seen as disclosing a connector for interconnecting first and second printed circuit boards, comprising a first housing of electrically insulative material including a base and opposed sidewalls defining a contact disposition area therebetween. A first contact set is supported in the first housing contact disposition area and is inclusive of a grounding contact disposed adjacent one of the sidewalls and carried thereby and signal contacts disposed in the base between the grounding contact and the other of the sidewalls. A second housing of electrically insulative material has a configuration complemental with the configuration of the first housing to be matable therewith and a second contact set is supported in the second housing including signal contacts engageable with the signal contacts of the first contact set upon mating of the first and second housings and a grounding contact again supported by the second housing sidewall and engaging the ground contacts of the first contact set upon mating of the first and second housings.
Of significance, expressed in the '518 patent, is that the ground contacts do not appreciably cause an increased crosswise dimension of the first and second connector housings, since such ground contacts are carried by the housing sidewalls and do not require additional PCB "real estate" above that required by the signal contacts. Further, the '518 patent sees as a matter of consequence that the contact disposition area of the first connector housing be free of the presence of connector housing electrically insulative material.
On the other hand, British Pat. No. 580,216 expressly shows the use of discrete slidingly engageable contact elements carried outwardly of an insulative body which further supports diverse other pin-socket contact elements, respectively for signal and ground interconnect.